Inclusion Criteria:Eligible patients, male and female, will be less than 80 years of age and be on stable levodopa. Subjects must have stable, bothersome dyskinesia and have an MDS-UPDRS score 2 or greater, on item 4.2. All anti-parkinsonian medications must be unchanged for at least one month prior to study enrollment. Subjects may be taking amantadine at a stable dose for at least one month prior to study onset -